WESTERN AFRICA

Most Western African countries are well-endowed with freshwater, except for
those bordering on the Sahel, which frequently experience drought. Accessibility
to freshwater and its integrated management nonetheless remain major concerns
in western Africa. Inappropriate management of freshwater, and competition between
user groups, limit efforts by governments and the international community to
encourage economic development and to improve the standard of living in western
Africa. There are also rising concerns over freshwater quality, in terms of
pollution from domestic effluents and industrial wastewater, particularly in
the coastal zone.

AVAILABILITY OF FRESHWATER IN WESTERN AFRICA

With the exception of Cape Verde, all the countries in the sub-region share
surface water resources with one or more other countries. The sub-region is
drained by three major basin systems. The Niger basin drains an area of 2 million
km2 (33 per cent of the total surface area of the sub-region), and
involves 9 of the 16 subregional countries, including Cameroon and Chad. Other
important basins are: the Senegal basin, shared by four countries; the Gambia
basin, shared by three countries; the Bandama basin in Côte d’Ivoire; the Comoe
basin, shared by four countries; and the Volta basin, shared by five countries.
The sub-region’s freshwater resources are unevenly distributed between countries.
Liberia, for example, has internal renewable water resources of more than 63
000 m3/capita/yr, and Mauritania has only 150 m3/capita/yr
(UNDP and others 2000). Temporal variation in rainfall is common throughout
the subregion, but only those countries in the northern Sahelian zone (Mali,
Mauritania, and Niger) regularly experience drought, whilst countries in the
wetter coastal belt are periodically affected by floods.

Three major types of groundwater aquifers are observed in the region, namely:
basement aquifers; deep coastal sedimentary aquifers; and superficial aquifers.
The availability of groundwater varies considerably from one type of substrate
to another, and according to the local levels of precipitation and infiltration,
which determine the actual recharge. In Mauritania, for example, internal renewable
groundwater resources are estimated at 0.3 km3/yr (FAOSTAT 1997),
and these are important sources of water for domestic use, irrigation and livestock
watering. About 400 000 people live in the 218 oases, and are dependent on 31
400 wells, extracting the water manually (FAOSTAT 1997). The water is used to
irrigate 4 751 ha of palm trees, with 244 ha of annual crops under them (FAOSTAT
1997).

Six Western African countries are expected to experience water scarcity by
2025, namely: Benin; Burkina Faso; Ghana; Mauritania; Niger; and Nigeria (Johns
Hopkins 1998). Climate change is predicted to bring about reduced rainfall and
increased evaporation in the areas to the north, advancing the rate of desertification
in the Sahel (IPCC 2001). Countries in the coastal zone may experience more
intense rainfall and increased run-off. Combined with existing high rates of
deforestation and degradation of vegetation cover, this could have serious consequences
for soil erosion and agricultural productivity.

Figure 2e.10: Water use by sector in Western Africa, 1900–2025

Source: Shiklomanov 1999

Access to freshwater resources in Western Africa

Demand for water has been steadily increasing in all sectors, as a result of
population growth; commercial agricultural expansion; and industrial development.
Current total withdrawal of water for domestic, industrial and agricultural
consumption is 11 km3/yr, and demand for water from all sectors is
expected to increase to some 36 km3/yr by 2025, as shown in Figure
2e.10 (UNDP and others 2000, Shiklomanov 1999).

The Volta and Niger rivers have been dammed to supply water for irrigation
and domestic consumption, as well as to generate hydroelectric power. However,
this has created problems of accelerated erosion in the coastal zone, as well
as marginalization of pastoralists, who are dependent on seasonal floods (for
example, Acreman 1999). Despite agriculture being the largest water user, accounting
for 70 per cent of all withdrawals in the sub-region in 1995 (Shiklomanov 1999),
irrigation potential remains largely untapped, especially in the Sudano-Sahelian
zone, where only 16 per cent (5.3 million ha) of potentially irrigated lands
have been developed (Falloux and Kukendi 1988).

Access to piped water and sanitation also remains low, despite considerable
improvements during the International Drinking Water Supply and Sanitation Decade
(1981–1990). In 2000, total water supply coverage was highest in Senegal (78
per cent) and lowest in Sierra Leone (23 per cent), with most urban areas in
the sub-region better supplied than rural areas (WHO/UNICEF 2000).